This invention relates to a heat pot with a heater which maintains the temperature of hot liquid contained therein by heating the liquid with a heater.
A heat pot has been proposed with a vacuum container having excellent heat insulation properties. This vacuum container consists of an external and an internal tank, the space between the walls of which is vacuumized. The internal tank also serves as a reservoir tank to accommodate the liquid. This heat pot is provided with a heater or heat pipe that transmits heat from a heater, which is located within the internal tank passing through the vacuum region and heats the liquid within the internal tank. When this heat pot is used, only about one or two Watts of electricity is required to keep about 2 l of hot water at about 90.degree. C. A better heat insulation performance therefore exists when compared with conventional heat pots. However, since this kind of heat pot is generally made of metals such as stainless steel, heat from the heater may be transmitted to the external tank wall of the vacuum container via the portion through which the heater is passing, and thus leak to the outside of the vacuum container. Further, in the same way, the heat of the liquid within the internal tank may also leak to the outside via the heater and the portion of the vacuum container.
Another known heat pot has been proposed with a heater within the vacuum region of the vacuum container. In this heat pot, since the heater does not pass through the vacuum region, the heat from the heater or heat of the liquid within the internal tank almost never leaks out of the vacuum container. However common heaters gradually generate various gases from their resistance wires and micas, while metallic sheathed heaters do so from the magnesia electrically insulating the resistance wire from the metal sheath. As a result, in these types of heat pots, the gas generated from the heater is collected in the vacuum region reducing the degree of vacuum in this region. The reduction of the vacuum degree may deteriorate the heat insulation ability of the vacuum region. Further the structure of these types of heat pots suffer from the defect that when either the heater or the vacuum container is inoperable or broken, complete replacement of each is required.